The plants generally known as annuals, are raised from the seed, perfect their flowers, mature their seed the same season, and then perisn. There are some flowers, however, cultivated as annuals, that are such only in a northern climate, being in their own more congenial region perennials, or biennials. Among them are the Verbena, Chriseis, or Eschscholtzia, as it was formerly called, Commelina, Mirabilis, and many others. This class of annuals maybe kept through the winter in greenhouses or in any light cellars. Annuals are most appropriate for those who are changing their abode from year to year, as from these alone a fine display may be kept up the whole season, with the exception of the vernal months, and this deficiency-may be supplied by having- a choice collection of perennials, grown in pots, which can be plunged in the ground, and thus removed at any time when it is necessary to change the residence.
No collection of plants can be perfect without an abundance of annuals, as they can be disposed of in such a way as to succeed the perennials, and keep up a continuous bloom in all parts of the garden through the season.
Annuals may be divided as follows: - hardy, half-hardy, and tender.
Hardy annuals are such as may be sown in autumn or very early in the spring, as all the Larkspurs, Chriseis, Clarkea, Asters, Candytufts, etc. Half-hardy are those which will not bear a hard frost, and therefore not proper to plant in the open ground before the middle or last of May, as the Balsam, Cockscomb, Marigold, etc. Tender annuals can hardly be brought to perfection without starting them in artificial heat, in a hot-bed or otherwise, and are very sensitive of cold, as the Cypress vine, Thunbergia, Ice Plant, Sensitive Plant, etc. Many of these, in a very warm season, will succeed tolerably well if planted about the 1st of June; but to have them in perfection they should be raised in a hot-bed, in pots, and turned out in the ground the middle of June.
Before sowing annuals, the soil in which they are to be grown should be made light and rich, and very finely pulverized, as many of the seeds are very small, and require every advantage and care to get them up. The small seeds must receive but little covering, and that of the finest earth. In sowing these, my practice is to sow them in patches six or eight inches square. The soil having been well prepared, I settle the ground gently with the foot or a small piece of board, so as to make an even, somewhat firm, surface. The seeds are then evenly strewed over the surface. Then take some very fine soil and sift or strew over them, covering the seed not more than one eighth of an inch deep, after which press the 4 soil again with the board gently. It is now of great importance that the seeds, as they vegetate, should be protected from the scorching sun; an evergreen bough is as good as anything to shade them. The soil must not be permitted to get dry until the young plants have acquired some strength; after which they may be left to take their chance from the effects of sun or dryness. When the plants are of a proper size, and the weather suitable, they may be taken up with a transplanting trowel, and set where wanted. A small patch of this description will afford plants enough for any common garden. In removing them, a number may be taken up together without disturbing the roots; but when the plants have become established, all may be cutoff except the strongest ones. As a general rule, a single plant gives better satisfaction than when a number are grown together, except when planted in masses, or where there is to be a group. The beauty of many annuals is completely destroyed by huddling them together. Give every plant room according to its habits. A single plant, well trained, may be made very beautiful; while a number of the same species grown together, without sufficient room, would be worthless.
Larkspur, and many other seeds, should be sown where they are to remain. A bed of Double Rocket Larkspur, well managed, is almost equal to a bed of Hyacinths, when in bloom. This succeeds best when sown late in autumn or very early in the spring. The seed may be sown in drills, eight or ten inches apart, in beds, and the plants well thinned out. Larkspur, and many other hardy annual seeds, if sown late in autumn, and lie dormant all winter, will give much stronger plants than the same kinds of seed sown very early in the spring, notwithstanding those sown in the spring may appear above ground as soon as those sown in autumn. The reason probably is, that the autumnal sown seeds are so prepared, by the action of the frost, that they start with greater vigor, and consequently are more robust than the spring-sown seeds.
Some seeds are difficult to germinate. Cypress vine is an example. This requires scalding, to facilitate its germination; or, if the hull is carefully taken off with a penknife, so as not to injure the germ, the object is effected, and it will immediately vegetate. The seeds of Gomphrena globosa (Globe Amaranth) is encased in a thick coating of woolly substance, which greatly retards vegetation. This, with the hull, if taken off, causes the germ to push immediately; or, if the seed is soaked in milk twenty-four hours, it will soon start; but, if planted with the coating on, or without soaking, very few will appear above ground.
As a general rule, the depth of planting flower seeds is to be governed by the size. For example, the Sweet Pea and Lupine may be planted an inch deep, and so in proportion. Annuals have a pleasing effect when planted in masses, particularly when the pleasure-ground is extensive. For this purpose, the Verbenas, of various colors, Portulaccas, Nemophylla, Chriseis, Phlox Drummondii, Coreopsis Drummondii, Candytufts, and many other dwarf plants, are desirable. Beds of any of these, or others of similar habit, in a well-managed grass lawn, are very ornamental. The beds should be either round, oval, starry, or irregular; but never square, diamond shape, or triangular. Masses of annuals may be so arranged as to make a grand display in the common flower-garden. We have seen the walks of an extensive flower-garden deeply edged with a wide border of crimson and scarlet Portulaccas; and, throughout the whole garden, all the annuals, and other plants, in fact, were planted in masses. We have never seen a better managed garden than this one. It contained about an acre of ground. Not more than twenty or thirty kinds of annuals were cultivated in the garden, and of this class of plants more than one half of the ground was filled. They consisted of every variety of Double Balsams, German Asters, Drummond Phlox, Coreopsis, Amaranths, Verbenas, Portulaccas, Double China Pinks, Petunias, Mignionette, Cockscombs, Gilliflowers, etc.